Q128C Motor

[Deleted member 4366]

Wow! This motor rocks. I'm using the 201 rpm 36v version at 48v. I wasn't sure how much current to use, so I thought I'd start with only 15 amps. I made a mistake in trying to pedal away on level 5 because it made the front wheel jump up in the air. I went straight to my 14% test hill to test it's torque. It had no problem pulling me up without pedalling (all up weight about 109kg). Top speed unloaded is 29 mph, which is a bit faster than what I wanted. I didn't change anything else on my bike - still the same 48v Dolphin battery. The controller is from Kunteng, the same as the S06S from BMSBattery but 48v. On the road, it seems to have really good power throughout it's speed range way past 20 mph.

If you want a fast commuter without the weight of a massive battery and hub-motor, this motor on a good lightweight hybrid like the Boardman would work really well. It would also be good if you're a bit lardy and want to do a road-bike conversion. If you wanted the slower pace of an MTB, the 36v one would be better with increased current - say 20 amps for a top speed of about 19 mph on the road.

I must say that it's nice to have my 9-speed gears back after all these years - and that nice Shimano XT slick-shifting.

The bike looks exactly the same as before:

 

[tommie]

any comments on the noise?

what size of rims, 26"?

how hot does it get on the hills?

 

[Deleted member 4366]

It's s more or less silent when you're riding. The sine-wave controller probably helps.

I haven't taken it up any long hills yet, but I doubt that it'll get hot at only 15 amps.

26" wheels.

 

[tongxinpete]

I seem to remember problems surfaced with the two speed motor, would you recommend this above the two speed & indeed is it a step up from the good Q100H. I value simple and reliable above gimmicks, & like a throttle so could I team it with a Con91. Afraid it is a case of limited money for the build. I came to suspect that having the option to throw a few more amps into a well chosen hubbie (once moving on the level it probably uses no more than a smaller motor would) beats crank drive & multi speed. Say @ 36v nom I would need a batt with a C rate to cover the peak amps drawn on tough hills. Not sure weather to go 10Ah or 15Ah if I went down this road. BTW is it laced 1 cross or 2 cross into the 26'' rim?

 

[Nealh]

The 128C is barely audible a slight whirring but as d8veh say's a sw controller is a big help. At 36v I can cruise on the flat at 19.2 - 19.8 mph (700c & 20a ), it might be a bit lower if a gps was used to confirm it. I like mine and on hills level 5 is noticeable as full amps kick in.
Need to find a small bag to put my lipos in to give 12s ago.

 

[Deleted member 4366]

I seem to remember problems surfaced with the two speed motor, would you recommend this above the two speed & indeed is it a step up from the good Q100H. I value simple and reliable above gimmicks, & like a throttle so could I team it with a Con91. Afraid it is a case of limited money for the build. I came to suspect that having the option to throw a few more amps into a well chosen hubbie (once moving on the level it probably uses no more than a smaller motor would) beats crank drive & multi speed. Say @ 36v nom I would need a batt with a C rate to cover the peak amps drawn on tough hills. Not sure weather to go 10Ah or 15Ah if I went down this road. BTW is it laced 1 cross or 2 cross into the 26'' rim?

Nearly all the problems with the Xiongda 2-speed were from people that fitted them to trikes and recumbents. When you paddle them backwards with weight on the back-wheel, the clutch can lock which then puts a massive load on the sun gear and ring gear, so something breaks. it's not a problem on a bicycle because you don't need to paddle one backwards while sitting on it.

The Xionda is better for heavy riders who need that winch. Not many motors can match its torque in low gear. The Q128 at 48v has substantially more torque than your average small hub-motor. It certainly went up the 14% hill a lot quicker than an old Ezee bike I tested last week, which runs at 36v and 20 amps. if the weather's better tomorrow, I might try some of the very steep hills we have around here.

 

[NJS]

Nearly all the problems with the Xiongda 2-speed were from people that fitted them to trikes and recumbents. When you paddle them backwards with weight on the back-wheel, the clutch can lock which then puts a massive load on the sun gear and ring gear, so something breaks. it's not a problem on a bicycle because you don't need to paddle one backwards while sitting on it.

The Xionda is better for heavy riders who need that winch. Not many motors can match its torque in low gear. The Q128 at 48v has substantially more torque than your average small hub-motor. It certainly went up the 14% hill a lot quicker than an old Ezee bike I tested last week, which runs at 36v and 20 amps. if the weather's better tomorrow, I might try some of the very steep hills we have around here.

If you had to choose just one for general local commuting in moderately hilly terrain, which would it be?

 

[Deleted member 4366]

Moderate and steep hills = Q128c at 48v
Extreme hills or heavy rider and steep hills = Xiongda at 48v.

 

[NJS]

Moderate and steep hills = Q128c at 48v
Extreme hills or heavy rider and steep hills = Xiongda at 48v.

Thanks for your candor.

I believe you have owned and run XD2 motors supplied as both 36V and 48V motors. And that you've run the "36V" version at 44V/48V.

Is there any notable difference in the two when run at 48V, in terms of:
1) hill climbing ability;
3) reliability
2) flat road top speed;

Those are my 3 priorities in order of importance; and I'd greatly value your long-term, considered opinion in making my decision.

Thanks, njs.

 

[Deleted member 4366]

The 48v version of the XD has a slower winding, so it goes at approximately the same speed as the 36v one when both are at their nominal voltages. If you run the 36v one at 20 A and the 48v one at 15A, they have more or less the same performance, except that the 36v controller runs hotter.

There's no point in running the 36v one at a higher voltage because you lose the climbing efficiency.

Top speed is about 22 mph with a charged battery. Low gear is 12 mph maximum, though it's more like 10 mph because you'd only use it on a hill.

I did about 4000 miles on mine before swapping to the Q128C. I had to grease it at the begining and it was probably ready for another regrease when I took it off. That was to get rid of a sort of hollow resonance noise, which I don't believe is anything harmful, but it's just a bit annoying because the motor is otherwise silent.

The Q128 can handle more power, is easier to install and is less complicated. As I said, the XD is for ultimate climbing torque or for towing heavy loads. I switched over to the Q128 because I found I very rarely used the XD's low gear, even on pretty steep hills, after my fitness improved and weight went down a bit.

 

[NJS]

I did about 4000 miles on mine before swapping to the Q128C. I had to grease it at the begining and it was probably ready for another regrease when I took it off. That was to get rid of a sort of hollow resonance noise, which I don't believe is anything harmful, but it's just a bit annoying because the motor is otherwise silent.

The Q128 can handle more power, is easier to install and is less complicated. As I said, the XD is for ultimate climbing torque or for towing heavy loads. I switched over to the Q128 because I found I very rarely used the XD's low gear, even on pretty steep hills, after my fitness improved and weight went down a bit.

Only one question left to ask: Where did you buy your Q128, and how much did you pay?

(Oh. and one more last question [strike]You have the Q128C variant. Is that 201 or 328 rpm and is it 36V or 48v?[/strike] Edit: I just realised that this is answered in the first post above. D'oh!)

Thanks, njs.

 

[Nealh]

Only available here.
https://bmsbattery.com/ebike-kit/768-q128c-135mm-500w-rear-driving-ebike-hub-motor-ebike-kit.html

 

[NJS]

Only available here.
https://bmsbattery.com/ebike-kit/768-q128c-135mm-500w-rear-driving-ebike-hub-motor-ebike-kit.html

Okay, thanks.

I had "found" them, but I wondered if there was an alternate supplier that I might have missed.

Also, they list several controllers and displays; any recommendations?

 

[SPYDER]

Hi Dave. This looks like it might be a great motor for my project. I'm looking to build a more "road" focussed bike with a higher top speed than my Xiongda MTB. Around 22-24 top speed ideally, probably using a Spesh Cirrus or similar. Could be 700c or 26" wheels. If I used the same motor as you, the 36V one running at 48V, would this mean that the motor is out of its efficient band at say 22mph?
Would you pick the Kunteng controller over the BMSB one and what displays would it work with?
And on the subject of the Xiongda failures, well, the centre nylon gear on mine failed some time ago. Its replacement failed after 10 miles, the whole nylon assembly was spinning on the centre pinion. Apparently they had sent me one which hadn't been welded yet! The next one is still going strong. I have repaired the "spinning" one by bonding and pinning it together. So I have a "spare", just in case.

Thanks, Geoff.

 

[Nealh]

All BMSB S series controllers are KT models as is the 09 base for dolphin /09 batteries. Any of the lcd's from lcd1 to lcd6 will work, lcd3 upwards have the extra C parameter settings and screen extras.

In theory all new S series controller should be compatible with most KT lcd's produced over the last 2/3 years. I have lcd1, 2 & 3 and all work with my S series KT's, to be 100% sure buy them as a pair.

 

[Deleted member 4366]

The Q128C would be perfect for that spees. By all accounts, the 36v 201 rpm and the 48v 328 rpm are in fact the same motor apart from the label, so you can take your pick. I have the 36v 201 rpm at 48v in a 26" wheel. I have it limited to 15.5 mph, but even at that speed, it seems to be pretty efficient. It has plenty of torque, but I have a feeling that it would work better in a 26" wheel than 700C.

 

[petr]

"By all accounts, the 36v 201 rpm and the 48v 328 rpm are in fact the same motor..."

Are the other two versions (36v 328 rpm and 48v 201 rpm) realized by different winding or different gear ratio?

 

[Deleted member 4366]

"By all accounts, the 36v 201 rpm and the 48v 328 rpm are in fact the same motor..."

Are the other two versions (36v 328 rpm and 48v 201 rpm) realized by different winding or different gear ratio?

I don't know about the Q128c, but the 48v 201 rpm Q128H is definitely 201 rpm. It does 19 mph with a fully-charged 48v battery in a 26" wheel.

It doesn't make much sense to use the 328 rpm 36v motor unless you have a bike with small wheels.

The Q100s get their different speeds with different gear ratios.

 

[petr]

Thank you, Dave, for a fair answer. The idea (please correct me somebody if I am wrong) is that from motors of the same construction, voltage and weight, the highest efficiency will have the motor with the fastest rotor (regardless of the resulting RPM). This is due to best energy conservation in a given mass. Therefore from the Q100 family the strongest motors in low RPM (where the efficiency matters most) are reported those with the highest gear ratio.
I wonder if the same will be later found by Q128C.

Petr

 

[Deleted member 4366]

As a general rule, the faster the rotor spins, the more the specific power and the higher the efficiency. That's for motors of similar size and construction.